Neural stimulation, such as peripheral nervous system (PNS) stimulation (e.g.,) techniques like vagal nerve stimulation (VNS), can provide therapy for many chronic diseases including epilepsy and depression. When stimulating nerves, such as in the PNS, it can be especially difficult to position electrodes to be in close proximity to nerve fascicles, at least because of the nerve's epineurium layer. As a result, electrical stimulation can be very inefficient.
Current design limitations with respect to electrode placement within a peripheral nerve also limit the ability to sense data associated with the nerve. Current PNS electrode placement options are inadequate for providing a sufficiently high signal-to-noise ratio of sensed neural activity. Current PNS electrode placement results in sensed signals frequently being largely overrun by other nearby electrical activity, such as electrocardial activity and electromuscular activity. As a result, current neural stimulation schemes generally operate in an open-loop fashion, without direct electrical feedback from the nerve.
Additionally, current techniques for PNS electrode placement often rely upon compressing the nerve between flat, opposing plates lined with sharp electrodes. Compression of the nerve into a flattened shape may allow the individual fascicles within the nerve to spread apart in the flat plane, thus allowing the plurality of electrodes to puncture the nerve at locations adjacent individual neurons. However, this technique is rudimentary at best and long-term use may result in complications due to compression of the nerve.
Some techniques for PNS electrode placement rely upon manual application of force to pierce the epineurium of the nerve, and possibly the perineurium of a fascicle. Manual application of force is generally performed relatively slowly, especially because of the risk of damaging surrounding tissue. Also, the force applied to pierce the epineurium can inadvertently damage the nerve, including the fascicles within. Some techniques attempt to minimize the amount of pressure applied during implantation, often relying on sharp electrodes to focus force onto a single point on the epineurium. While these sharp electrodes pierce the epineurium, they also carry a high risk of piercing or damaging a fascicle.